In order to observe a minute region of an object, a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like is used. In general, in these apparatuses, a housing for disposing the sample is evacuated and the sample is captured by evacuating the sample atmosphere to make the atmosphere to a vacuum state. However, in a case where a water-containing sample, such as a biological sample or a liquid sample, is damaged or the state thereof changes due to the vacuum state. Meanwhile, since there are substantial needs for observing such a sample using an electron microscope, an SEM apparatus which is capable of observing an observation target sample under the atmospheric pressure, or under the desired gas pressure or type of gas, is strongly desired.
In recent years, an SEM apparatus which is capable of disposing the sample under the atmospheric pressure, or under the desired gas pressure or type of gas, by providing a diaphragm or a minute hole through which an electron beam can transmit between an electron optical system and the sample, and by partitioning the state into the vacuum state in which the electron beam flies and the state under the sample atmosphere, is known. In PTL 1, a case where a sample under the atmosphere is SEM-observed in a state where a diaphragm and a sample are not in contact with each other using a sample stage disposed immediately under the diaphragm, and a position of the sample for the observation is adjusted, is disclosed.